America hasn't faced a direct conventional threat to the continental United States in a long time. We've had the luxury of fighting "over there" rather than "over here". Technology is changing that.
American production, transportation (railroads, ports, and airfields in particular), and logistics assets in the lower 48 states (CONUS, or the Continental United States) are no longer part of a sanctuary that can project power overseas unhindered by enemy action. Cruise missiles need to be stopped before they confine our military power to North America.
Defending the homeland from cruise missile attack is a higher priority:
The Pentagon’s plan to defend the U.S. homeland from cruise missiles is starting to take shape after a prolonged period of development because until recently, the threat was perceived as a more distant regional one, a senior Air Force official said.
North American Aerospace Defense Command and U.S. Northern Command have been working for several years and across two presidential administrations to come up with a design that can effectively defend the continental U.S. from cruise missiles, according to Brig. Gen. Paul Murray, NORAD deputy director of operations.
Sure, there was a time when fighter planes and air defense missiles were deployed widely across America. But those were to defeat nuclear-armed bombers.
And recently we have built thin ballistic missile defenses.
But there are limits to what we can do:
CSIS, in a report it debuted at the conference, said it will be impossible to protect everything. Lt. Gen. A.C. Roper, U.S. NORTHCOM deputy commander, said in a recording played at the event, that “placing a Patriot or a [Terminal High Altitude Area Defense] battery on every street corner is both infeasible and unaffordable.”
Focused defense is in order. America hasn't worried about protecting our assets to project power abroad since the Army had coastal defense artillery to protect our ports.
That ability to project power without worrying about threats to the homeland has been the key to our global power and influence. But we need not only the free power to project abroad, but the ability to project that power.
Yet cruise missiles with precision targeting could prevent America from projecting our reserve power abroad to support allies. I've worried about our fleet at home. With good reason. Now we have to guard our infrastructure.
